Insulating and refractory composition and elements for the lining of metal casting molds incorporating such compositions



United States Patent 3 Claims. (Cl. 161-162) ABSTRACT OF THE DISCLOSUREA lining for ingot hot tops, comprising an insulating layer in contactwith the ingot top, and consisting of 15 to 40% by weight a comminutedsilica, 15 to 45% by weight of fireclay, 4 to 12% by weight ofkieselguhr, 7 to 15% by weight of wood flour, and 0 to 11% by weight ofasbestos fiber, and a refractory layer consisting of 40 to 80% by weightof grains of 0 to 0.2 mm. of fireclay, 5 to 24% by weight of grains of0.3 to 1 mm. of fireclay, 0 to 6% by weight of wood flour, and 0 to 11%by weight of asbestos fiber, the elements being agglomerated in eachlayer by means of a phenolic synthetic resin present in an amountbetween 7 to 11% by weight of the other elements of the layer.

It has already been proposed to incorporate with the lining of shrinkageholes or contraction cavities and of the tops of ingot molds used forcasting metal, elements made of a material having as a base aninsulating and/or exothermic composition. In US. Patent No. 3,344,838dated Oct. 3, 1967, for Method for Producing an Exothermic Lining for'lngot and Foundry Molds and Hot Tops, there is disclosed :a method forforming runners, according to which the heat capacity of the insulatingmaterial is compensated by a layer of exothermic material extending incontact with the metal, in a manner such that the insulating layer mayreach its temperature of equilibrium without removing any heat from themolten metal forming the runner.

In the case of the formation of runners on parts or ingots of a largeweight, the heat capacity of the material forming the insulating liningelements of the shrinkage holes or of the top of the ingot mold isnegligible with reference to the heat inertia of the metal mass formingthe runners.

Furthermore, by reason of the substantial height required for therunners in the case of large ingots or large cast parts, the ferrostaticpressure exerted on the lining is such that the compositions ensuring agood thenmic insulation are not sufficiently refractory and consequentlythe products forming such compositions are decomposed or disaggregatedand the massive linings are crushed by the cast metal.

My invention has for its object to remove said drawback and it coversmore particularly a lining, chiefly lining elements molded before theirfitting in shrinkage holes and tops of ingot molds; according to myinvention, said elements are constituted by a highly insulating layer incontact with the top of the ingot mold, which layer is lined by arefractory layer in contact with the metal.

The insulating layer has preferably the following composition:

Percent by wt.

Siliceous sand or siliceous meal 15-40 5 Fireclay 15-45 Kieselguhr orlight infusorial earth 4-12 Wood meal 7-15 Asbestos fibers 0-11 Theabove mixture is bound by a synthetic resin the percentage of which withreference to the total amount of solid products mentioned hereina'boveranges between 7 and 11% by weight.

The refractory layer has preferably the following composition:

Percent by wt. Fireclay in grains (between 0 and 0.2 mm.) 40-80 Thismixture which has a high refractory power is bound by a synthetic resinthe percentage by weight of which with reference to the total amount ofsolid products listed above ranges between 7 and 11%.

For the formation of the total thickness in registry with the runnersand also for certain other applications, the so-called insulating layermay also be used alone in ditficult cases with the possible formation ofa protecting coat thereon.

The lining is preferably supplied in the shape of preformed elementsshaped by any suitable method, chiefly by molding a paste diluted withwater, the percentages of water ranging between 25 and 750% by weight ofthe total amount of solid material. The paste may be drained without anyrisk of loss of any components during its shaping as provided by moldingunder pressure or else in association with filtering or in accordancewith any other molding method without any risk of the Water carryingaway the non-soluble components. The lining elements when they have beengiven the desired shape may be dried at C. with a view to cutting outthe residual water that they may still contain.

In the case of a shaping of the elements by a filtering method theinsulating layer or the refractory layer is first molded by settlingover a suitable thickness after which the other layer is caused tosettle on the first layer by filtration through the said first layer.

It may be mentioned that for the lining of the shrinkage holesregistering with the runners for a steel ingot weighing 4 metric tons, Iuse plates 320 mm. high and 30 mm. thick carrying over their surface arefractory layer of a thickness of 8 'mm. coated by an insulating layer22 mm. thick.

The composition of the refractory layer was as follows:

Percent Fireclay (between 0 and 0.2 mm.) 76 Fireclay (between 0.3 and 1mm.) 10 Asbestos of the amosite type -11 Sawdust 3 said solid materialsbeing bound by means of a phenolic resin at the rate of 8% by weightsaid solid materials being bound by 9% by weight of phenolic resinmeasured with reference to the total amount of solid products mentionedhereinabove.

The shrinkage hole, after soldification showed an excellent appearance,without substantial crushing of the lining.

The compositions disclosed hereinabove by way of example in anon-limiting sense [may be modified to some extent within the scope ofthe accompanying claims.

What I claim is:

1. A premolded element chiefly for the lining of the shrinkage holes andthe tops of ingot molds comprising an insulating layer constituted by 15to 40% by weight of comminuted silica, 15 to 40% by weight of fireclay,4 to 12% by weight of kieselguhr, 7 to 15% by weight of wood meal and upto 11% by weight of asbestos fibers, together with phenolic syntheticresin the amount of which ranges between 7 and 11% by weight of thetotal weight of the precedingly mentioned components and a refractorylayer consisting of 40 to 80% by weight of fireclay of which the grainsize is comprised between and 0.2 mm., 5 to 25% by weight of fireclay ofwhich the grain size is comprised between 0.3 and 1 mm., 0 to 6% byweight of wood flour and 0 to 11% by weight of asbestos fibers, and aphenolic synthetic resin the amount of which ranges between 7 and 11% byweight of the total weight of the precedingly mentioned components, saidrefractory layer covering the insulating layer.

2. A highly insulating layer for incorporation in a lining chiefly forshrinkage holes and tops of ingot molds constituted by 15 to by weightof comminuted silica, 15 to 40% by weight of fireclay, 4 to 12% byweight of kieselguhr, 7 to 15% by weight of wood meal and up to 11% byweight of asbestos fibers, together with phenolic synthetic resin theamount of which ranges between 7 and 11% by weight of the total weightof the precedingly mentioned components.

3. A refractory layer for incorporation in a lining, chiefly forshrinkage holes and tops of ingot molds, constituted by 40 to by weightof grains of 0 to 0.2 mm. of fireclay, 5 to 24% by weight of grams of0.3 to 1 mm. of fireclay, up to 6% by weight of Wood meal, up to 11% byweight of asbestos (fibres and a phenolic synthetic resin binderweighing between 7 and 11% of the total weight of the precedinglymentioned components.

ROBERT F. BURNETT, Primary Examiner.

WILLIAM J. VAN BALEN, Assistant Examiner.

